The present invention relates to methods and storable hardenable resin compositions for forming one or more fractures in high temperature subterranean zones and consolidating proppant particles therein.
Hydrocarbon producing wells are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing, a viscous fracturing fluid, which also functions as a carrier fluid may be pumped into a subterranean zone to be fractured at a rate and pressure such that one or more fractures are formed in the zone. Proppant particles, e.g., graded sand, for propping the fractures open may be suspended in the fracturing fluid so that the proppant particles are deposited in the fractures when the fracturing fluid is broken. That is, a viscosity breaker may be included in the fracturing fluid so that the fracturing fluid reverts to a thin fluid, which may then be returned to the surface. The proppant particles deposited in the fractures may function to prevent the fractures from closing so that conductive channels are formed through which produced hydrocarbons can readily flow.
To prevent the subsequent flow-back of the proppant particles as well as loose or incompetent fines with fluids produced from the subterranean zone, the proppant particles have heretofore been coated with a hardenable resin composition which is caused to harden and consolidate the proppant particles in the zone into permeable packs. However, when the subterranean zone has a temperature above about 200° F., and it produces hydrocarbons at exceptionally high rates or undergoes reoccurring stresses due to frequent well shutoffs and openings, the hardened resin composition and the permeable proppant particle packs consolidated therewith rapidly deteriorate thus allowing proppant particles and formation fines to flow back with produced formation fluids. The flow-back of the proppant particles and formation fines is detrimental in that it erodes metal goods, plugs piping, and vessels and causes damage to valves, instruments, and other production equipment.
Another problem encountered in the use of prior hardenable resin compositions for coating proppant particles is that the hardenable resin composition or components thereof have had short shelf lives. In addition, the hardenable resin composition components have heretofore had low flash points making them dangerous to use. Also, when the prior hardenable resin compositions or components thereof have been stored at high ambient temperatures, the compositions or components have quickly hardened making them unsuitable for use.
Thus, there are needs for improved methods and storable hardenable resin compositions for consolidating proppant particles in subterranean fractures whereby the permeable packs of consolidated proppant particles formed may be resistant to degradation by high production rates, stress cycling, and/or thermal degradation. Further, there are needs for improved hardenable resin compositions that are premixed and have long shelf lives and high flash points.